Mophead Type hydrangea in Jonesborough, TN garden

Mophead hydrangeas (Hydrangea macrophylla), the blue/pink flowering species, have been the gardening rage since the early 1990’s. Endless Summer® hydrangea started a wave of new repeat blooming (remontant) cultivars. They bloom on both  new season’s as well as old wood from the previous year. These hardier cultivars extended the flowering time by 8 to 10 more weeks and bloomed in cooler climates formerly unable to grow mopheads.

To add to your success, here are additional tips on growing mopheads:

“The Right Plant In The Right Location” rule strongly applies to mopheads. The farther north you grow mopheads, the more sunlight they can handle. In USDA hardiness zones 4 thru 5-a, plant in a sunny location which receives a minimum of 6 hours of sunlight. Reduce to 4-5 hours of mostly morning sunlight in zones 6 and 7, and grow in high shade in zone 7-b to 9.

Protect Against Severe Winter Temps and Spring Freezes: Hydrangea buds openvery early. Late spring freezes frequently destroy or injure flower buds and new growth. Keep the crown (plant base) heavily mulch to mid-May in northerly areas.

Feeding: Fertilize with a slow-release fertilizer such as 10-30-10 or equivalent in early spring. For example, the phosphorus (30% P) level should be 2-3 times greater than the nitrogen (10% N) or potassium (10% K) levels. Container plants may need an extra bi-monthly feedings of a water soluble fertilizer. Over-feeding hydrangeas may result in dark green leaves (a good thing) and fewer flowers (not so good). In USDA zones 4 and 5, do not fertilize past August 15th, as it may lead to winter injury.

Watering: Mophead hydrangeas have large fleshy green leaves and insist on growing rapidly. Overwatering may lead to few or no flowers at all. On hot summer days, it is normal for mopheads to wilt for a short period in mid-day. It’s best to irrigate thoroughly once weekly, usually 1 ½ inches of water, than to water a little bit every day.

Pruning: Mopheads should not be cutback in the fall like other hydrangea species. Flower buds are borne on old wood for late spring flowering. Remember: the remontant type of hydrangeas bloom on both old and new wood.